Can you tell me which power source should I buy, to activate a 3-6V dc motor? I’d like to use a motor rotating at 60rpm, like this one: https://www.sparkfun.com/products/13258. I don’t want to fry everything once I connect it. Should I use a 9V battery?
It should swing a rope connected to a 20gr weight, in a hypnotic way.
Can tell me which potentiometer should I buy to add the possibility to change the speed, I’m not sure where to find it for a small motor like this one.
9V is > than 3V or 6V, you probably don’t want to connect 9 volts if your motor only needs 3 or 6.
A 2 AA battery holder will give you 3 volts, a 4 AA battery holder will give you 6 volts. I’d go with either one of those.
A potentiometer on it’s own won’t work to control speed, a motor will require more power than a potentiometer is capable of delivering. You need a speed controller for that OR, you could use a 2 AA battery holder and a 4AA battery holder and use a switch to choose either one. That would give you 2 different speed choices.